Custom packets for ItemExchange trade displays

plugins/civmodcore-paper/src/main/java/vg/civcraft/mc/civmodcore/mods/packets/CivModPacketHandler.java

@@ -0,0 +1,16 @@
+package vg.civcraft.mc.civmodcore.mods.packets;
+
+import com.google.gson.JsonElement;
+import net.kyori.adventure.key.Key;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+
+public interface CivModPacketHandler {
+    public static final CivModPacketHandler NOOP = (sender, packetId, json) -> {};
+
+    public void handleCivModPacket(
+        @NotNull Player sender,
+        @NotNull Key packetId,
+        @NotNull JsonElement json
+    );
+}

plugins/civmodcore-paper/src/main/java/vg/civcraft/mc/civmodcore/mods/packets/CivModPackets.java

@@ -0,0 +1,125 @@
+package vg.civcraft.mc.civmodcore.mods.packets;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonElement;
+import java.nio.charset.StandardCharsets;
+import java.util.Objects;
+import net.kyori.adventure.key.Key;
+import org.bukkit.Bukkit;
+import org.bukkit.entity.Player;
+import org.bukkit.plugin.java.JavaPlugin;
+import org.bukkit.plugin.messaging.Messenger;
+import org.jetbrains.annotations.NotNull;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class CivModPackets {
+    private static final Logger LOGGER = LoggerFactory.getLogger(CivModPackets.class);
+    private static final Gson GSON = new Gson();
+
+    public static void registerPacket(
+        final @NotNull JavaPlugin plugin,
+        final @NotNull Key packetId,
+        final boolean registerIncoming,
+        final boolean registerOutgoing,
+        final @NotNull CivModPacketHandler handler
+    ) {
+        Objects.requireNonNull(plugin);
+        Objects.requireNonNull(packetId);
+        Objects.requireNonNull(handler);
+        final Messenger messenger = Bukkit.getMessenger();
+        if (registerIncoming) {
+            messenger.registerIncomingPluginChannel(plugin, packetId.toString(), (channel, sender, payload) -> {
+                final Key receivedPacketId;
+                try {
+                    receivedPacketId = Key.key(channel);
+                }
+                catch (final Exception e) {
+                    LOGGER.warn(
+                        "{} sent a packet with an invalid packetId: {}",
+                        sender.getName(),
+                        channel,
+                        e
+                    );
+                    return;
+                }
+                final JsonElement json; {
+                    final String raw = new String(payload, StandardCharsets.UTF_8);
+                    try {
+                        json = GSON.fromJson(raw, JsonElement.class);
+                    }
+                    catch (final Exception e) {
+                        LOGGER.warn(
+                            "{} sent a packet [packetId:{}] with an invalid payload: {}",
+                            sender.getName(),
+                            receivedPacketId,
+                            raw,
+                            e
+                        );
+                        return;
+                    }
+                }
+                LOGGER.info(
+                    "{} sent packet [packetId:{}]: {}",
+                    sender.getName(),
+                    receivedPacketId,
+                    json
+                );
+                try {
+                    handler.handleCivModPacket(sender, receivedPacketId, json);
+                }
+                catch (final Exception e) {
+                    LOGGER.warn(
+                        "Something went wrong while handling {}'s [packetId:{}] with payload: {}",
+                        sender.getName(),
+                        receivedPacketId,
+                        json,
+                        e
+                    );
+                }
+            });
+        }
+        if (registerOutgoing) {
+            messenger.registerOutgoingPluginChannel(plugin, packetId.toString());
+        }
+    }
+
+    /// Use this to register incoming-only packets. If the packet is bidirectional, use [#registerPacket] instead.
+    public static void registerIncomingPacket(
+        final @NotNull JavaPlugin plugin,
+        final @NotNull Key packetId,
+        final @NotNull CivModPacketHandler handler
+    ) {
+        registerPacket(plugin, packetId, true, false, handler);
+    }
+
+    /// Use this to register outgoing-only packets. If the packet is bidirectional, use [#registerPacket] instead.
+    public static void registerOutgoingPacket(
+        final @NotNull JavaPlugin plugin,
+        final @NotNull Key packetId
+    ) {
+        registerPacket(plugin, packetId, false, true, CivModPacketHandler.NOOP);
+    }
+
+    public static void sendPacket(
+        final @NotNull JavaPlugin plugin,
+        final @NotNull Player recipient,
+        final @NotNull Key packetId,
+        final @NotNull JsonElement json
+    ) {
+        final String payload = GSON.toJson(json);
+        LOGGER.info(
+            "Sending packet to {}: [packetId:{}]: {}",
+            recipient.getName(),
+            packetId,
+            payload
+        );
+        recipient.sendPluginMessage(
+            plugin,
+            packetId.toString(),
+            payload.getBytes(StandardCharsets.UTF_8)
+        );
+    }
+}
+
+

plugins/civmodcore-paper/src/main/java/vg/civcraft/mc/civmodcore/utilities/KeyedUtils.java

@@ -1,7 +1,9 @@
 package vg.civcraft.mc.civmodcore.utilities;
 
+import io.papermc.paper.plugin.provider.classloader.ConfiguredPluginClassLoader;
 import org.bukkit.Keyed;
 import org.bukkit.NamespacedKey;
+import org.bukkit.plugin.java.JavaPlugin;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -70,4 +72,27 @@ public static NamespacedKey testKey(@NotNull final String key) {
         return new NamespacedKey("test", key);
     }
 
+    public static @NotNull NamespacedKey of(
+        final @NotNull Class<? extends JavaPlugin> pluginClass,
+        final @NotNull String value
+    ) {
+        /// This code is based on [JavaPlugin#getPlugin] but avoids accessing the plugin instance itself, making this
+        /// safe to use even when a plugin instance doesn't necessarily exist yet.
+        if (!JavaPlugin.class.isAssignableFrom(pluginClass)) {
+            throw new IllegalArgumentException("%s does not extend %s!".formatted(
+                pluginClass.getName(),
+                JavaPlugin.class.getName()
+            ));
+        }
+        if (!(pluginClass.getClassLoader() instanceof ConfiguredPluginClassLoader classLoader)) {
+            throw new IllegalArgumentException("%s was not loaded by %s!".formatted(
+                pluginClass.getName(),
+                ConfiguredPluginClassLoader.class.getName()
+            ));
+        }
+        return new NamespacedKey(
+            classLoader.getConfiguration().namespace(),
+            value
+        );
+    }
 }

plugins/itemexchange-paper/src/main/java/com/untamedears/itemexchange/ItemExchangePlugin.java

@@ -5,6 +5,7 @@
 import com.untamedears.itemexchange.glues.jukealert.JukeAlertGlue;
 import com.untamedears.itemexchange.glues.namelayer.NameLayerGlue;
 import com.untamedears.itemexchange.rules.ModifierRegistrar;
+import com.untamedears.itemexchange.rules.ShopRule;
 import com.untamedears.itemexchange.rules.modifiers.BookModifier;
 import com.untamedears.itemexchange.rules.modifiers.DamageableModifier;
 import com.untamedears.itemexchange.rules.modifiers.DisplayNameModifier;
@@ -16,6 +17,7 @@
 import java.util.List;
 import vg.civcraft.mc.civmodcore.ACivMod;
 import vg.civcraft.mc.civmodcore.commands.CommandManager;
+import vg.civcraft.mc.civmodcore.mods.packets.CivModPackets;
 import vg.civcraft.mc.civmodcore.utilities.DependencyGlue;
 
 /**
@@ -54,6 +56,7 @@ public void onEnable() {
         modifiers.registerModifier(BookModifier.TEMPLATE); // 1000
         registerListener(new ItemExchangeListener());
         this.glues.forEach(DependencyGlue::registerGlue);
+        CivModPackets.registerOutgoingPacket(this, ShopRule.SHOW_TRADE_PACKET);
     }
 
     @Override

plugins/itemexchange-paper/src/main/java/com/untamedears/itemexchange/glues/namelayer/GroupModifier.java

@@ -33,10 +33,8 @@ public final class GroupModifier extends ModifierData {
     // Make sure to have a template instance to make registration easier
     public static final GroupModifier TEMPLATE = new GroupModifier();
 
-    private static final String ID_KEY = "id";
     private static final String NAME_KEY = "name";
 
-    private int groupId;
     private String groupName;
 
     @Override
@@ -51,18 +49,18 @@ public boolean conforms(final ItemStack item) {
 
     @Override
     public boolean isBroken() {
-        return false;
+        return this.groupName == null;
     }
 
     @Override
     public void toNBT(final @NotNull NbtCompound nbt) {
-        nbt.setInt(ID_KEY, getGroupId());
-        nbt.setString(NAME_KEY, getGroupName());
+        if (this.groupName instanceof final String groupName) {
+            nbt.setString(NAME_KEY, groupName);
+        }
     }
 
     public static @NotNull GroupModifier fromNBT(final @NotNull NbtCompound nbt) {
         final var modifier = new GroupModifier();
-        modifier.setGroupId(nbt.getInt(ID_KEY, 0));
         modifier.setGroupName(nbt.getString(NAME_KEY, null));
         return modifier;
     }
@@ -76,7 +74,7 @@ public List<String> getDisplayInfo() {
 
     @Override
     public String toString() {
-        return "%S{%s:%d}".formatted(getSlug(), getGroupName(), getGroupId());
+        return "%S:%s".formatted(getSlug(), getGroupName());
     }
 
     // ------------------------------------------------------------
@@ -104,7 +102,6 @@ public void commandSetGroup(final Player player,
                 return;
             }
             final GroupModifier modifier = handler.ensureModifier();
-            modifier.setGroupId(group.getGroupId());
             modifier.setGroupName(group.getName());
             handler.relay(ChatColor.GREEN + "Set trade to group \"" + group.getName() + "\"");
         }
@@ -114,14 +111,6 @@ public void commandSetGroup(final Player player,
     // Getters + Setters
     // ------------------------------------------------------------
 
-    public int getGroupId() {
-        return this.groupId;
-    }
-
-    public void setGroupId(final int groupId) {
-        this.groupId = groupId;
-    }
-
     public String getGroupName() {
         return this.groupName;
     }

plugins/itemexchange-paper/src/main/java/com/untamedears/itemexchange/glues/namelayer/NameLayerGlue.java

@@ -25,7 +25,7 @@ public void denyPurchaseIfNotGotPerms(final BrowseOrPurchaseEvent event) {
             final GroupModifier modifier = event.getTrade().getInput().getModifiers().get(GroupModifier.class);
             if (!Validation.checkValidity(modifier)
                 || PermissionsGlue.PURCHASE_PERMISSION.testPermission(
-                GroupManager.getGroup(modifier.getGroupId()), event.getBrowser())) {
+                GroupManager.getGroup(modifier.getGroupName()), event.getBrowser())) {
                 return;
             }
             event.limitToBrowsing();

plugins/itemexchange-paper/src/main/java/com/untamedears/itemexchange/rules/ShopRule.java

@@ -4,21 +4,27 @@
 
 import com.google.common.collect.Lists;
 import com.google.common.collect.Sets;
+import com.mojang.serialization.JsonOps;
 import com.untamedears.itemexchange.ItemExchangeConfig;
 import com.untamedears.itemexchange.ItemExchangePlugin;
 import com.untamedears.itemexchange.events.BlockInventoryRequestEvent;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Set;
+import net.minecraft.nbt.NbtOps;
 import org.apache.commons.collections4.CollectionUtils;
 import org.bukkit.ChatColor;
+import org.bukkit.NamespacedKey;
 import org.bukkit.block.Block;
 import org.bukkit.block.BlockFace;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.Inventory;
 import org.bukkit.inventory.ItemStack;
 import org.bukkit.util.BlockIterator;
 import vg.civcraft.mc.civmodcore.inventory.InventoryUtils;
+import vg.civcraft.mc.civmodcore.mods.packets.CivModPackets;
+import vg.civcraft.mc.civmodcore.nbt.NbtCompound;
+import vg.civcraft.mc.civmodcore.utilities.KeyedUtils;
 import vg.civcraft.mc.civmodcore.utilities.Validation;
 import vg.civcraft.mc.civmodcore.world.WorldUtils;
 
@@ -28,6 +34,7 @@
 public final class ShopRule implements Validation {
 
     private final ItemExchangePlugin PLUGIN = ItemExchangePlugin.getInstance();
+    public static final NamespacedKey SHOW_TRADE_PACKET = KeyedUtils.of(ItemExchangePlugin.class, "trade-details");
 
     private final List<TradeRule> trades = new ArrayList<>();
 
@@ -84,19 +91,36 @@ public void presentShopToPlayer(Player player) {
         if (trade == null) {
             throw new NullPointerException("Could not message player about trade... this shouldn't happen.");
         }
+        final int currentTradeIndex = this.currentTradeIndex + 1, tradesCount = this.trades.size();
         player.sendMessage(String.format("%s(%d/%d) exchanges present.",
-            ChatColor.YELLOW, this.currentTradeIndex + 1, this.trades.size()));
+            ChatColor.YELLOW, currentTradeIndex, tradesCount));
         for (String line : trade.getInput().getDisplayInfo()) {
             player.sendMessage(line);
         }
-        if (trade.getOutput() != null) {
-            for (String line : trade.getOutput().getDisplayInfo()) {
+        int stock = 0;
+        if (trade.getOutput() instanceof final ExchangeRule outputRule) {
+            for (String line : outputRule.getDisplayInfo()) {
                 player.sendMessage(line);
             }
             PLUGIN.debug("[ShopRule] Calculating stock.");
-            int stock = trade.calculateStock();
+            stock = trade.calculateStock();
             player.sendMessage(ChatColor.YELLOW + "" + stock + " exchange" + (stock == 1 ? "" : "s") + " available.");
         }
+        // Mod support
+        final var displayNbt = new NbtCompound();
+        displayNbt.setInt("trades", tradesCount);
+        displayNbt.setInt("index", currentTradeIndex);
+        displayNbt.setCompound("input", trade.getInput().toNBT());
+        if (trade.getOutput() instanceof final ExchangeRule outputRule) {
+            displayNbt.setCompound("output", outputRule.toNBT());
+            displayNbt.setInt("stock", stock);
+        }
+        CivModPackets.sendPacket(
+            ItemExchangePlugin.getInstance(),
+            player,
+            SHOW_TRADE_PACKET,
+            NbtOps.INSTANCE.convertTo(JsonOps.INSTANCE, displayNbt.internal())
+        );
     }
 
     // ------------------------------------------------------------

plugins/itemexchange-paper/src/main/java/com/untamedears/itemexchange/utility/nbt/NBTSerializable.java

@@ -6,6 +6,12 @@
 
 @Deprecated
 public interface NBTSerializable {
+    default @NotNull NbtCompound toNBT() {
+        final var nbt = new NbtCompound();
+        this.toNBT(nbt);
+        return nbt;
+    }
+
     /**
      * Serializes this class onto a given NBTCompound.
      *